Apparatus for the manufacture of zinc oxid.



J. A. SINGMASTER.

APPARATUS FOR THE MANUFACTURE OF ZINC OXID. u

APPLIGATION FILED JAN. 18, 1912.

Patented Oct. 6, 1914.

10 SHEETS-$113151 l.

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APPARATUS FOR THE MANUFACTURE OF ZINC OXID.

APPLICATION FILED JAN.18,1912.

Patented Oct. 6, 1914.

10 SHEET3-SHBE'1 2 AAA Vfiwss es. J/ZVM/ 7/ 7 [A XCZWM J. A. SINGMASTER. APPARATUS FOR THE MANUFACTURE OF ZINC OXID.

APPLICATION FILED JAN.18,1912.

1 ,1 12,854. Patented Oct. 6, 1914.

10 SHEETS-SHEBT 3.

J. A. SINGMASTER.

APPARATUS FOR THE MANUFACTURE OF ZINC OXID.

APPLICATION FILED JAN. 18, 1912. Patented Oct. 6, 1914.

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APPLICATION FILED JAN. 18, 1912.

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J. A. SINGMASTER.

APPARATUS FOR THE MANUFACTURE OF ZINC OXID.

APPLICATION FILED JAN. 18,1912.

1,1 12,854. Patented 001;. 6, 1914.

10 SHEETS-SHEET 6 3 Il/l/I/ll/ll/Illl/ 00 0 o b 0 o o o o o 0 co e 0 o o o o o 0 o o o o o J. A. SINGMASTER.

APPARATUS FOR THE MANUFACTURE OF ZINC OXID.

APPLICATION FILED JAN. 19, 1912.

1,1 12,854. Patented 001;. 6, 1914.

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APPARATUS FOR THE MANUFACTURE OF ZINC OXID.

APPLICATION FILED JAN.18, 1912.

1, 112,854. Patented Oct. 6, 1914.

10 SHEETS-SHEET 8.

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APPARATUS FOR THE MANUFAGTURE OF ZINC OXID.

APPLIOATION FILED JANJB, 1912.

1,1 12,854. Patented Oct. 6, 1914.

10 BHEETS-SHEET 9.

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Wdfizeasea. 29 V5 ifidL'Z/ZZUI? (A Z UNITED STATES PATENT OFFICE.

JAMES ARTHUR SINGMASTER, OF PALMERTON, PENNSYLVANIA, ASSIGNOR TO NEW JERSEY ZINC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

APPARATUS FOR THE MANUFACTURE OF ZINC OXID.

Specification of Letters Patent.

Patented Oct. 6, 1914.

Application filed January 18, 1912. Serial No. 671,821.

siding at Palmerton, Carbon county, State of Pennsylvania, have invented certain new and useful Improvements in Apparatus for the Manufacture of Zinc Oxid; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the I same.

The object of the invention is to provide a practical means for producing zincoxid by a continuous operation and in such manner that the sublnmng reactions,

called, will be effected with a higher degree of chemical and mechanical efficiency than is possible with-the Well known form of lVethcrill furnace.

More particularly, the object of the -in-' vention is to save fuel and labor, to increase the percentage of yield from the charge and improve the uniformity and purity of the product, to simplify the operations and apparatus required for handling the raw material and the residuum, and, further, to ameliorate the temperature conditions to which the workmen are subjected.

According to my invention, the charge is placed on a moving conveyance, specifically formed as a traveling grate-surface, and advanced through the combustion zone of the furnace apparatus, wherein the deslred re- I nature of. the material to be treated. the

charge may be spread on a layer of bed coal, which has been ignited, or'it may be deposited on the conveyance in any other suitable way, while the conveyance is advancing into or through the furnace, ignition. of the fuel being produced either by special means. to this end or spontaneously by the heat of the zone; and,coincidently with the advancing movement, a suitable fuming charge.

combustion-supporting gas, such as air, is transmitted to or through the charge in controlled amounts to the end of properly generating the fume from the zinc or from the other volatile metal in the charge. After the fume generation has ceased, the conveyance moves out of the combustion zone, bearing a residuum of barren clinker and ash, which is given opportunity to cool before it emerges from the structure, and is required to be handled by the workmen. The effluent is drawn ofiduring the passage of the charge and conducted toappropriate receivers. The preliminary etlluent, being a gas of the general character of producergas, and having little or no metallic content, is or may be conducted to a point separate from the fume-collecting means, where its fuel value may be utilized, or it may be wasted if preferred; but in either case the receivers for the sublimed product are not burdened with the necessity of cooling and filtering this high temperature and non-metallic part of the efliuent from the charge. The preliminary metallic-fume efiiuent, being the effluent evolved in the initial stages of the reaction, is usually more or less impure and off-color as a pigment, and for this reason is preferably conducted and recovered separate from the subsequently evolved fume. The fume rising from the charge after it has reached the stage of full combustion, is transmitted to baghouses or other suitable screening system for collection in the usual way. It is important that the. fume constituting the objective product of the process be taken awa promptly from the sublimingrcgion and thereforethe screening and collecting system 'is connected with such region through a plurality of suitable off-takes distributed at intervals along the path of travel of the These off-takes may .all lead to the same receiver, if desired, with or without a suction fan to move the fume through them; but it will be obvious that they can be connected singly or in groups to separate receivers so that not only the fume containing sooty particles, if any such fume, but also fumes of different composi'tions can be separately collected from the same charge. It is by virtue of this method of removing the eflluent .from the traveling charge, that bituminous coal can be used as 110 remain, can be kept separate from the white 1105 the fuel, as above stated. The preliminary non-metallic effluent will contain the greater part of the sooty combustion products, and what remains thereafter will pass either into the first or second succeeding off-takes.

which are in this case, of course, connected with separate receivers.

The combustion or sublimin zone above referred to, is preferably constituted by the middle part of a long, stationary, thickwalled chamber or tunnel which is raised to the necessary high temperature by the heat of the reactions taking place therein, and is maintained at that temperature by the continuing passage of the charge, without being allowed to cool down iintil the end of the run, thus establishing practically constant temperature conditions and .a consequent high degree of uniformity in the quality of the product pigment. The traveling grate surface on which the charge is carried, is divided into sections, as later described, each following the other .and each provided with its own air supply connections which are subject to control by the operator so as to maintain a proper temperature of charge and furnace and a suficient excess of oxygen above the charge to oxidize the volatilized metal. or metals. As in the established Wetherill practice, the air that is supplied to the charge is increased as combustion progresses and-the charge advances. Further control of the generation of the fume can be had inthe present invention by varying the suction in the off-takes, and by varying the rate .of movement of the charge, such movement being accelerated or retarded, as the case may be, in accordance with the conditions developing in the charge as observed through suitable openings in the tunnel side-walls. ment' may, of course, be continuous or intermittent according to circumstances, and it will be seen that by the exercise of proper judgment in the regulation of the controlling factorsxthe conditions that are now known to be most productive of economy of operation-and of hlghquality of product in Wetherill-furnaces can obviously be 'reproduced-by my apparatus in continuous form,-

and that such conditions can also'be maintained with a high degree of reliability. and precision.

In the mixture constituting'the metallic 5 compound to be reduced and volatilized, -the fuel ingredient (which may be anthracite coal or bituminous 0051) will necessarily be somewhatlarger in my method tharrjust a sufiicient for the generation of thenecessary 0 heat and the reduction of the metal, and myinvention further contemplates the treat? ment of the char e after the volatile metal g has been extracte to recover and utilize the energy of this excess. .By continuing the 35 air current through thecharge and moving The advancing movethe latter to a point beyond the subliming zone, the fuel remaining therein is con verted into gas which I conduct back to the furnace at an earlier point in the path of the charge, or utilize in some other manner, as will belater' ointed out. This gas may, .if desired be mlxed or used in conjunction with the preliminary, non-metallic effluent given offby the entering ignited charge as above explained before it reached the point of generation of fume.

' From the outlineof the principal features of my invention, above given, it will be seen that the continuous process I have devised, readily lends itself to performancein duplicate or multiple apparatus, whereby the grate sections leaving one furnace tun-- nel can be immediately dumped, or cleaned and again loaded and entered into another tunnel, and while they are still fairly hot, so that the ignition of the new charge thereon will be assisted and time as well as fuel saved.

ltfis the object .of the apparatus to provide siinple and effective means for trans porting and advancing a charge and for" -maintaining its temperature and the control of the reactions, whereby uniformity can be obtained and whereby such manual labor as is required to be performed thereon can be done at a safe distance from the region of intense heat. r

it should be noted, and will be apparent'to those who are skilled in the art of subliming metals, that both the method and the apparatus constituting the invention herein disclosed, are also applicable to the manufacture of sublimed metallic products other than zinc-oxid.

Referring to the drawings: Figures 1 and 1 together represent a wertical, cen- .tral and longitudinal section of a tunnel.

structure embod ing the present invention] andadapted to t e method I have above def. m

iscribed; Fig. 2 is an enlarged detail in ver- ,tical section 'throughthe tunnel and one of the grate sections, on line II-IIyof Fig. 3; IF ig. 3 a transverse vertical section of Fig. 2, the structure being here shown as a single Ztunnel structure; Fig. 4 ahorizontal section 'on line-lVIV of Fig. 3; Fig. 5 a vertical longitudinal section on the staggered line V.V of Fig.-3;- Fig. 6 a horizontal section ,tion on'line X-X- of Fig. 9; and Fig.11 is ovided-nwith a. modified and prev a side elevation, partly insection, of a modifiedform of furnace structure.

The tunnel structure 1, is built of masonry with a thick arched roof and preferably also withthick side-walls, so as to be capable of confining and retaining the high degree of heat necessary for the subliming process. It's length may be about 150 feet and its internal dimensions about 7 by 6 feet, sub- 10 ject to variations, however, as circumstances may require. The length is determined with relation to the time required for complete volatilization and oxidation of all the zinc or volatile metal of the charge during the v-movement of the latterthrough the tunnel at a definite rate, a slower rate of movement requiring a longer tunnel, and vice Versa. The tunnel is preferably somewhat longer than required to accommodate the traveling charge while in the actual process of combustion, so that its end portions may serve as vestibules, so to speak, of the actual combustion region, the entrance portion being adapted to protect the charge during its formation and ignition, and the exit portion to allow the exhausted charge to cool off before emerging, while the extension of the tunnel at either end, beyond the limits of the actual combustion zone, operates to conserve "the heat developed by the reactions in the latter. In the drawings, the length of the tunnel is reduced for convenience, by breaking out the intermediate parts, but the portion constituting the active combustion zone is indicated in a general way by the location of the off-takes which are for carrying away' the gaseous product and fume. The interior of the tunnel is provided with a series of partitions 2, depending from the roof, with their lower edges extended as close'as may be to the top of the charge moving thereunder. These partitions serve as baflies obstructing movement of gas between the combustion zone and the ends of the tunnel, and divide the upper part of the tunnel into a series of inverted pockets or collecting hoods into which the fume from the charges rises and from which it is collected. In Figs. 1 to 10, the partitions are formed by arched curtain-walls sprung from the sides of the tunnel, as shown more clearly in Fig. 3, but in the modified tunnel structure of Fig. 11 the same effect is produced by forming the tunnel roof of a series of successive arches 3 'with their axes transverse to the direction of the tunnel and their springers rested on cross beams 4 spanning theside walls of the tunnel. The cross beams and their enveloping 6 masonry, being situated just above the course of the charge, serve the same purpose as the bafile partitions 2 of the form first described.

Water pipes, indicated in section at 4* in Fig. 11, are laid alongside the beams 4 to guard against their overheating.

The partitions, formed in either way, are

located at intervals. throughout the length of the-tunnel excepting at the entrance end where they may be omitted to provide space for charging. Throughout the portion of the tunnel where the charge is in combustion, they are spaced apart at substantially regular intervals of say about '12 feet, and from eachof the intervening pockets leads an offtake for the effluent gas or fume. The first off-take 5, is adapted to conduct the preliminary non-metallic efliuent which is given off by the charge after ignition but before volatilization of metal has begun. There may be several off-takes for this kind of effluent but only one is illustrated in the drawings. It or they may lead to any suitable collectoror to a chimney stack, but as above mentioned the preferred method of operation contemplates the utilization of these gases for heating or igniting the bed-coal, and for this purpose a down-comer 6 is provided for the structure shown by Fig. 1 leading to the chamber or region of the tunnel where the charging operation takes place. The gas is directed toward the freshly-laid fuel bed together with the air necessary for its combustion, and the heat thus generated is made use of toignitethe fuel. In case this fuel supply should not be sufficient for this purpose, as may be the case in starting the apparatus in action, I have arranged an auxiliary furnace, indicated diagrammatically at 6 in Fig. 1 which is adapted to provide suificient heat to insure ignition of the fuel. The combustion gases of the ignition stage may be wasted in any suitable Way. The second off-take 7, considering them with reference to the advancingmovement of the charge, is intended to take away the preliminary metallic efliuent, being for this rea son entirely independent of the remaining off-takes. It may lead to a bag-house or any suitable receiver not shown in the drawings. the next succeeding off-takes 8 lead off from the part of the tunnel where the subliming actions take place and are for the fume resultinsr from the perfect reactions of the charge. These off-takes may all be connected with a common pipe or flue 9 running to the bag-house or, where the material under treatment is capable of fractional subliming, the successive off-takes can be separately used for collecting the difierent fumes evolved. Dampers are dia ammatically indicated at 40 in each off-ta e for controlling the movement of the fume or gas therethrough Each of the charge-carrying grate-sections marked 10 in the drawings, is mounted on a wheeled truck-frame running on a trackway 12 laid on the floor of the tunnel, and is of suitable width to extend from side-wall to side-wall of the tunnel with only a running clearance on either side.

The successive grate-sections or them supporting frames are" adapted to move in endwise contact with each other, so that they will form a moving and substantially continuous horizontal deck or partition, dividing the upper from the lower part of the tunnel with no appreciable gap or opening between them. The clear ance spaces at the sides of the traveling sections are preferably sealed by lutes. These may consist of troughs 13 carried on brackets on the side walls of the tunnel and filled with sand or other heavy and mobile material. The grate-sections have aprons 14 depending from their lateral margins and projecting into the sand so as to form a continuous closure, adapted to accommodate the movement of the sections without leakage. The particular mode of mounting and guiding the sections through the tunnel is not of special consequence, and various other means than the wheeled truck frames can manifestly be used with like effect, but the wheeled frame or buggy, such as shown, is

preferred because of the length of the tunnel and the load which must be carried through it. The lower part ofthe tunnel is open to the circulation of the outside atmosphere and is therefore not so heated as to injure the running gear of these devices. Each truck frame is a rectangular frame about 12 feet long with a free space in the middle for the accommodation of the air supply apparatus and the water basin. The side-sills, marked 15, are borne directly on the journal boxes 16 securedto them, and are joined 'at their ends by the cross-sills 17 On the top of each side-sill, there is planted a series of slotted brackets 18, and across the rectangular frame there is laid a series of eight or more bearer-bars 19 rested with their ends in the slotted brackets, so that their top edges occupy substantially the same horizontal plane. A plurality of separate and re movable grate bars, each about 9 inches wide and perforated, such as are at present used in zinc-oxid furnaces, are laid side by side uponthe bearing bars with their ends supported in the angles of the Z-bars 20, of which there is one at each end of the frame, to hold the grate bars from longitudinal moyementon the frame. The two grate bars located at the sides of the section, and marked 10, are preferably secured to the frame, so that they willhold the intermediate removable bars from separating laterally. The several bearer bars 19 support the grate bars against sagging when highly heated under the weight of the charge, and

' these bars are formed in simulation of knife edges, as shown, so that they will perform grate perforations. These juxtaposed grate furnace. Upright walls are preferably conthis function without unduly obstructing the structed on the margins of eachsection to confine the charge thereon. The fixed grate bars 10 have placed upon them the bars 21, each of which is specially shaped to hold a row of refractory blocks 22 forming a side wall on each side of the grate; and end walls therefor are similarly provided by the bars 24 and the refractory blocks 23 held thereby, the four walls being preferably removablefromthe grate sectlon so that they can be lifted off separately or all together, to allow the clinker to be removed and the grate bars to be cleaned. The walls assist in the production of uniform quality of product by the facility they provide for leveling the charge off with a uniform depth,

equal to their height, over the surface of the grate and they also serve to retain and confine the heat as well as to avoid the erosion of the inner surface or lining of the furnace, which would otherwise take place if the stationary sides of the tunnel were relied 011 to keep the charge on the grate.

' The grate bars form the roof or covering of an air chest 25 formed of sheet iron in the present instance, with sloping side walls which are secured by their lateral upper margins to the side sills and by their end margins to the depending flanges'of the two end Z-bars 20. The space between the side sills and the fixed grate bar 10 on one side is closed in by the curved wall 26 (Fig. 3) while the corresponding space on the other side is left open for the admission of the air, which on entering the chamber passes thence upd wardl-y through the perforations in the bars and through the charge thereon. A handhole, in the form of a flap-door 27, normally perature in the grate.

Admission of the air to the air-chest 25 is accomplished by means of a device herein termed a traveling air connector, since its function is to form a connection between the charge conveyance with which it moves, and a stationary source of air supply, or a series of such sources, disposed along the path through the tunnel. This device is susceptible of embodiment in a variety of forms and may be used with forms of furnace apparatus varying considerably from the one under description.

- In the'form illustrated in Figs. 1 to 6 the connector consists ,of a depending box-like pipe or arm 28 equal, in its horizontal dimension to the length of the frame, and connected at its top with the air admission space of the air chest. For this purpose its upper margins may be secured respectively to the fixed grate-bar 10 and the top of the adjacent side-sill, as shown, and it may also be stayed to the journal boxes so that it will constitute a rigid structural part of the vehicle. Its lower end opens inside of a trough or gutter 29, whichis filled with liquid such as water and extends the full length of the track-way through the tunnel and parallel therewith. This trough or gutter, though shown below the level of the track rails, could be equally as well placed above that level. At intervals less than the length of the grate sections, the trough 29 is provided with upright air pipes 30 connected from beneath with the valved branchpipes 31 of a main air header which is supplied with air under pressure from a fan or like device shown in Fig. I. The upright pipes form a series of stationary air supply points throughout the length of the tunnel, one or more of which is adapted to project upwardly into the box-like pipe 28, of the grate section delivering air thereto, while the surrounding liquid furnishes a seal to the connection between the two. At its front and rear ends the box-like pipe is provided with hinged flap-doors or gates 2S partly or wholly submerged in the sealing liquid and adapted to ride over the tops of the upright air supplypipes as the vehicle advances, thus establishing air communication with the successive air pipes. It is desirable that the space between the adjacent supply pipes hefsuch that there will be at least one communicating with each air connector at every point in the movement of the latter-through the tunnel so that the air communication with the airchcst of each section will be continuous during the subliming process and under control.

It will be understood that all of the sections of the grate are similarly equipped with individual air supply connections of the kind described or the equivalent, so that as each is detailed to service it may move on the track-way through the tunnel with its air connector trailing through the water seal trough 29, each truck abutting closely against its adjacent trucks in front and rear,

so that the successive grate sections of each truck form a continuous traveling chargecarrying device as above described. The air connector pipes of each truck also abut or nearly so, so that the escape of air through the interval between them when riding over a supply pipe will not be excessive. The trucks may be propelled by any means suitable for the propulsion of vehicles, as for instance by a cable, but I prefer a pushing device such as the ram 33 indicated in Fig. 1, because the successive sections can be thus more readily kept in close contact with each other with no appreciable gap between them,

but with'other modes of propulsion, means for positively closing the intervening spaces can be readily added when desired. Switching devices and suitable trackage, not shown herein, are intended to be provided for introducing the trucks in position in front of the pusher. The track through the tunnel ispreferably on a lower level than that in the yard or approaches, so that the trucks will move down an incline, indicated at 52 (Fig. 1), as they enter the tunnel and thus bring their connectors and lute aprons 14 into the proper relation with the water and sand troughs, moving up a similar incline,

at the exit, as shown at 53, to disengage these parts.

The grate sections are preferably loaded with their charge as they enter or while they are within the tunnel, and for this purpose I have shown two hoppers above the tunnel roof; the one nearest the entrance, marked 34, is supplied with the fuel to form the bed which fuel passes, under control, through an inlet opening in the tunnel roof on to the grate surface of one of the sections 10, being spread thereon by means of a depressible spreader 35, manipulated by the lever diagrammatically shown at 36 or by any equivalent or suitable gearing, to cause the fuel to be spread in an even layer over the grate as the latter advances. As the grate surface thus covered with fuel comes under the second hopper 37, it receives therefrom a layer of mixed fuel and ore or such compound of zinc or of such other metal as may be the subject of the treatment. This hopper also is associated with a spreader 38, under the control of the operator, by which the charge is leveled off even with the tops of the side walls in the obvious manner.

In the drawings, the construction of the hoppers, their controlling devices and the spreaders, is indicated merely in a conventional way; it will be understood that any suitable mechanical appliances can be used for these purposes.

Being thus continuously loaded with a uniform layer of charge, the sections are continued in motion and pass toward and through the intermediate and highly heated part of the tunnel, heretofore designated as the active combustion zone. In starting the apparatus after a period of idleness it Will be necessary to ignite the entering charge by means of the special heating means above described and shown at 6 in Fig. 1, until the furnace is in full operation, after which the preliminary effluent from the down-comer 6 can be used for this purpose, or the gas from the residuary fuel, after completion of the fume generation as above stated.

By the proper regulation of the valves in air pipes 31, the air supply to each moving grate section is controlled in accordance with the observed physical and thermal condition The controlling valves in the branch pipes 31 are located along the tunnel so as to be conveniently operable from a position adj acent the doorways 39, through which the action of the charge is observable so that the adjustment of the air supply can be promptly -'.-eifected. WVhen the metal has become com- 15 pletely volatilized from the charge on a given grate section that section will have reached a point in the tunnel beyond the last off-take 8, and the effluent rising therefrom, resulting from the continuing combustion of the fuel still remaining in the charge, is allowed to pass through a lateral flue 42 in the side-wall of the tunnel, and thence either to a chimney stack or to some point where the heat therein can be utilized. At the point where the combustion of the remaining fuel has ceased or diminished and the air supply is discontinued, the grate sections pass under a pendent screen 43 hanging from the roof of the tunnel near the exit, which screen they push aside, as shown in the drawings. This screen and the two spreaders 35 and 38 all cooperate in closing in the ends of the tunnel structure above the level of the grate sections and they are each constructed with this end. in view. The length of the tunnel beyond the pendent screen can of course be continued as far as desired, and at the terminal thereof suitable mechanism will be arranged for removing the now exhausted charge.

The duplication of the tunnel apparatus referred to above is illustrated by Figs. 9 and 10 and its construction will be obvious'from a considerationof these figures, both tunnels being exactly alike except as to the reversal of their direction. Having a common dividing Wall 45, the two adjacent tunnels are, of course, more economical of heat than either would be if built separate. The formation and arrangement of the gratesections and their truck frames and the air connectors of each frame may be the same as already described, but the propelling means of whatever kind emp'loyed,'is arranged to move them in opposite directions through theirrespective tunnels so that the unloaded trucks of one tunnel can be immediately recharged and turned intothe adjacent entrance of the other with the. least loss of time and heat and the minimum of trackage and appliances. A loop of track or a turntable, not

shown, may be used for shifting the trucks from one tunnel to the other.

'The portion of each of the adjacent tunnels, between the last fume off-take and the pendent screen, is connected, by a lateral flue marked 46, leading through the dividing wall 45 into the entering portion of the adjacent tunnel, where the grate sections are receiving their bed-coal, or where they pass after having received it, and this latter portion of tunnel is connected with a stack or chimney 47. The fuel remaining in the charge after the volatilization of the metal, is caused to burn while moving in the portion of the tunnel above referred to by continuing the supply of air through the traveling air-connector, and. the products of combustion escapethrough the lateral opening 46 into contact with the freshly laid fuel in the entrance portion of the adjacent tunnel, where they may mingle with the preliminary non-metallic effluent if the same is used for igniting fuel. The escape from this part of the tunnel is through a chimney 47 The modification of Figs. 7 and 8 concerns only the form of air-connecting means, the construction of the tunnel and the truck frames and their grate surfaces and air chest being otherwise the same as above described. The air supply disposed along the track through the tunnel, comprises an inverted trougl1like box or hood 48,-coextensive in length witl the trough 29 which, as above described, runs the length of the tunnel. The open side of the hood is immersed in the water in the trough and its interior is divided into compartments by a series of flap-doors 49 hinged therein so that the effect of gravity will maintain them in closed position. Each compartment is connected through its side wall with one of the valved branch pipes 31 of the main air header 32, so that the pressure in .each of the compartments or the volume of air passing thereto can be varied at will and each independently of the others. The air-connector for this form of. air supply consists of a goose-neck pipe 50 connected by its upper end with the air chest 25 and terminating at its lower end in an upward extension 51 projecting within the hood 48 and reaching the space therein' above the water level, so that it can receive the air from the respective branch pipes 31 while the surrounding water. forms the seal to the connection. As the grate section travels along the track. the lower end of the gooseneck pipe will push upon and open the successive compartment doors 49, which will close behind it, and preserve the isolation of each compartment, except for the momentary interruption. when the pipe passes from one compartment to the next. The traveling grate sect-ions will be maintained in. constant communication with the air source. and in each of'them the air will be under control by the manipulation of the air valves, so that it can be made to increase as the charge advances or as desired. Ordinarily the supply to several compartments will be permanently set or adjusted to provide the appropriate increase in the supply to the trucks as they advance and without attention by the operator. The compartments of the inverted hood would then contain air at differential pressures properly coordinated to the advance of the charge. The goose-neck form of traveling air-connector is preferably hinged and telescopic, so as to be capable of being removed or turned back out of the way when the truck is being shifted about the yard, and it is hence more convenient than the form first described. One of the said pipes is sufficient to maintain constant communication with the fixed air source, but two or more of such pipes can be used with each truck frame, as indicated in the figures referred to. It is desirable, however, that the air boxes of the successive frames, when supplied with more than one air connector pipe, be arranged so that they will not put more than two of the compartments in the hood 48 in communication at the same time. This is accomplished by the proportioning of the spaces between the flap-doors 49 with reference to the spaces between the air connectors.

It will be understood by those skilled in this art that the apparatus above described is not limited with respect to thesize or proportion of the tunnel structure, or its gratesections, nor to the details of their mechanical assemblage or construction, nor to the number of air boxes supplied to the section of the grate surface that is borne by each truckkframe, and that various omissions, substitutions and alterations in the form and in the operation of the apparatus may be made without departing from the invention.

Having thus described my invention,

what I claim is:

1. A subliming furnace, comprising a refractory tunnel structure, a traveling grate surface adapted to move therein, means for transmitting combustion-supporting gas through said traveling grate surface, and a plurality of fu n'e off-takes connected With said structure at intervals along the length thereof. 1

2. A subliming furnace, comprising a fume collecting combustion chamber suitable for the generation of metallic fume, a

grate surface adapted to enter therein .divided in sections, each section having independent draft-current supplying means movable therewith, and suitable means for I removing metallic fume from the chamber.

3. A subliming furnace, comprising a combustion space or chamber having a fume-collecting roof portion and suitable for inclosing' a fume-generating charge,

combined with a charge-carrying conveyance adapted for moving into and out of said chamber and divided into sections having individual air-supplymg devices, and means for independently varying the sup ply of air through such devices.

4. A subliming furnace, comprising a tunnel structure, a continuous charge-carrying conveyance divided into sections having individual provisions for supplying combustion-supporting gas to the charge thereon, a track-way for said grate sections extending through the structure and means for collectin and conducting the effluent from the trave in charge.

5. A subliming furnace, comprising a tunnel structure suitable for confining the, generation of metallic fume, and having fume-conducting means connected therewith, a continuous perforate grate surface adapted for movement through the structure and divided into sections, each having provision forindependently supplying air to the charge thereon and means for varying the individual supplies to such sections.

6. A subliming furnace, comprising a tunnel structure suitable for the generation of metallic fume, .a continuous traveling grate surface dividing the upper from the lower part of said tunnel, means for transmitting air through said grate surface in progressively increasing volume during its passage through the tunnel, and fume-con ducting means connected to the tunnel roof.

7. A subliming furnace, comprising-a tunnel' structure suitable for generation of metallic fume, a charge-supporting conveyance adapted for movement through said tunnel, and means whereby an increasing air supply can be transmitted to the charge progressively with its movement tlierethrough, in combination with a plurality of fume offtakes leading from the tunnel structure at intervals along the path of the charge.

8. A subliming furnace, comprising a tunnel structure, a charge-supporting conveyance adapted for movement through the same, and means for supplying air to the charge, in combination with an off-take for non-metallic gas connected to the tunnel structure ata point near the entrance end thereof, and one or more off-takes for metallic fume connected to said tunnel at intermediate points along the path of the charge therethrough.

9. In a mechanical furnace, a traveling grate surface, composed of a series of movable, suitably guided supporting frames each having a perforated grate structure independent of the supporting frame and resting removably thereon and adapted to support the charge.

10. In a mechanical furnace, a traveling grate surface formed by a series of wheeled truck-frames having a series of juxtaposed grate liars independent of said truck-frames and removably supported thereon.

11. In a mechanical furnace, a series of truck-frames provided with removable, jux taposed grate bars forming a continuous grate surface independent of said truckframes and restin removably thereon and provided with Iateral charge-confining walls.

12 In a mechanical furnace, a traveling grate surface formed by a series of moving frames, each provided with a grate section and a wall or walls forming an air chamber, and means for varying the supply of air to said chamber.

13. In a subliming furnace, means for advancing a continuous charge of the compound to be volatilized, stationary means adjacent the path of the charge for supplying, an oxidizing aeroform medium thereto, and a traveling connector between such means and the traveling charge for transmitting the oxidizing aeroform medium into the charge. I

14;. In a subliming furnace, means for treating a continuous advancing layer of thev compound to be volatilized, comprising one or more air chambers having communication with the advancing charge layer and moving therewith, one or more stationary sources of compressed air disposed along the path of movement of said charge, and means providing a-traveling air-supply connection between said source or sources and the said air chamber.

7 sources of compressed air containing air of difi'erent pressures and disposed along the path of the advancing charge, and a moving air connector operative for conducting air from said stationary sources to the furnace 16. In a subliming furnace, a traveling charge-supporting device, a succession of sources of compressed air disposed along the ath of such device, and means movable with said device adapted for successive connection with the said sources of air.

' 17. In a subliming furnace, atunnel structure and a traveling charge-supporting device movable therein, in combination with an air or gas chamber moving with 'the charge and adapted for supplying air thereto, a stationary"- source of air supply and means including a liquid seal for conducting the air from said stationary source to the moving chamber.-

18. In a subliming furnace, tunnel structure suitable for the generation of metallic fume, a source of air pressure having fixed outlets within the structure, and a traveling charge-carrying device moving through said structure, bearing means for successive con nection with said outlets therein.

a ing charge,

. off-takes,

19. In a subliming furnace, a tunnel structure, a source of air supply having fixed outlets within the tunnel, a charge-carrying device movable in the tunnel, and having a traveling air connector forming a moving connection between the fixed outlets and the charge, and a trough or gutter containing a liquid formingasealed connection between the said outletsand the connector.

20, In a traveling-charge subliming furnace, means for supplying air to the travelcomprising an inverted hood or receptacle adapted for containing air and immersed in liquid, and an air pipe passing upwardly into said hood or receptacle through the liquid, one of said air-conducting or containing elements being stationary and the other movable through the liquid whereby air may pass from one to the other during their relative movement.

21. In a traveling-charge subliming furnace, means for supplying combustion-supporting gas to the travelingcharge, comprising a stationary inverted air-conductor or hood immersed in liquid, and a charge-carrying device having a pipe passing through the liquid to the interior of the said inverted conductor and movable lengthwise thereof. I I

22. In a traveling-charge subliming furnace, a furnace structure and means for supplying combustion-supporting gas to the charge traveling through said structure,

comprising a stationary inverted hood immersed in liquid, and divided into one or more normally closed compartments, 'a charge-carrying device having a pipe passing through the liquid into the interior of the hood, and means permitting assage of the pipe into and out of one o the compartments thereof.

t 23. In asubliming furnace, a tunnel struc- I ture suitable for the generation of metallic fume and provided with one or more fume a traveling .continuous grate surface and means for advancing the same into one end of said tunnel, through the same and out of the other end, in, combination with means ,for passing difierential supplies of air through said grate surface at different points between the ends of the tunnel.

24. In a subliming furnace, a fume collecting furnace structure suitable for. confining the generation of metallic fume, means for conveying a substantially continuous charge in or through the same and heating means adjacent the entrance to the structure for ignitin the entering charge. 25. A sublimin furnace comprising a chamber or. tunne structure suited for the generation of metallic fume and a traveling grate surface movable in or through the same, in combination with one or more 26. A subliming furnace formed as a tunnel structure suited for the generation of metallic fume and inclosing a track-way and a grate surface traveling thereon, one or more inlets for the charging materials in the roof of the tunnel and means for spreading and leveling such materials upon the traveling grate surface.

27. A subliming furnace comprising a structure with its roof portion divided internally into a plurality of fume collecting compartments or hoods and having means for removing the fume therefrom, in combination with means for passing a fuming charge beneath such roof portion.

28. A subliming furnace consisting of a structure superinclosing a traveling charge conveyance and provided with partition walls depending from the upper part thereof, and independent off-takes lea g from the spaces between the partitions.

29. Apparatus for subliming metallic compounds comprising two adjacent parallel tunnel structures provided with fume offtakes and combined with means for advancing the respective charges therethrough in opposite directions. I

30. Apparatus for subliming metallic compounds, comprising two adjacent structures each provided with means for advancing a fume producing charge therethrough, in combination with a connecting flue adapted for conducting gaseous matter from one to the other of said structures.

31. Apparatus for subliming metallic compounds comprising two adjacent tunnel or furnace structures having a common dividing wall and provided with grate surfaces adapted to move therethrough each of said structures being provided with a plurality of off-takes.

In testimony whereof I aflix my signature, in presence of two witnesses.

JAMES ARTHUR SINGMASTER. 

